Anti-idiotype antibodies (anti-Id) recognize determinants of the immunoglobulin variable region that are individually specific to the immunizing antibody. Fruitful in many scientific fields and promising in clinical trails of combination immunotherapy they are unfortunately one of the most laborious biological reagents to construct. In the course of tracing the origins of B cell malignancies we found that monoclonal anti-Id antibodies react with varying proportions (less than O.1-10%) of normal human B lineage cells. In the present study we will raise anti-Id antibodies and select for antibodies cross-reactive to a high proportion of human plasma cells and monoclonal immunoglobulins. Selected antibodies will be tested for preferential reactivity to Id+ antibodies of a particular isotype and for fine specificity by inhibition assays. The panel of existing and new anti-Id antibodies will be used to screen for expression of cross-reactive Ids by B cell malignancies and human immunoglobulins of clinical and research interest. this approach could spare patients and researchers the long delay in producing tailor-made anti-Id antibodies providing them with reagents for immediate use to monitor or treat B cell disorders. A panel of cross reactive antibodies would lower the cost of anti-Id production and enhance their role in clinical research